10 Species That Would Dominate if Humans Died Out

So, it finally happened. The zombies rose up, Putin hit the nuclear button, scientists created a killer virus, Yellowstone super-volcano erupted, and the apes turned on their human masters. The consequence: bang, no more humanity. Just you. The last list-reading human on Earth.

As you stand in the detritus of our society, like an extra from a depressing episode of the Twilight Zone, you might spare a thought for the civilization that will come after us. What will they look like? Where will they evolve from? Will they screw up as badly as we did?

Well, as a final service to humankind, we can answer those first two questions for ya. Deep within the nuclear-proof TopTenz bunker, our irradiated writer-mutants have put together one final list. A list of who might take over our mantle of top dog, and rule this post-apocalyptic wasteland you now find yourself standing in. Here they are, each more-horrific than the last…

10. The Rats

Rats love disasters. No matter where, no matter when, if there’s a large-scale catastrophe, you can bet a swarm of rats will be there. That’ll be as true for the apocalypse as it was for post-firebombing Dresden. The moment humanity collapses, rats will take over the cities; giant waves devouring everything in their path.

We’re not even at the fun bit yet. That comes much, much later, when rats have eaten all the dead humans and all their remaining food. According to Richard Dawkins, there’s a chance those rats may start to super-evolve.

The apocalypse will cause rat numbers to unsustainably explode. When the food and corpses run out, the rodents will be forced to turn on each other. This will lead to an extremely high-turnover rate of generations, coupled with possible radiation-triggered mutations, and a newfound isolation as different rat populations are cut off from one another in the post-human, post-transport world. In other words, the ideal conditions for evolution.

Given that rats already have complex social structures and surprisingly-high intelligence, there’s a chance they could wind up evolving in a similar direction to humanity. Sure, it’d take millions of years, and may not happen at all, but Dawkins believes a future intelligent species descended from rats isn’t as far-fetched as we’d like it to be.

9. The Bears

Humans are unquestionably masters of the planet. Even our natural predators flee at the sight of us wielding our guns and portable bazookas. As such, no other intelligent, large mammal has ever got a chance to carve out a niche for itself. But take humans out the equation, and suddenly creatures like lions and bears are back on top again. Leave them in that spot long enough, and they might just start to show something like human-level intelligence.

That’s the opinion of evolutionary and behavioral ecology post grad student Ashley Bennison at the University of Exeter, England. In an interview with PS Mag, he cited bears as the most-likely large mammal to seize our mantle in a post-human world. The argument goes like this: without humans, fewer animals will be eaten, leading to a boom in herbivores. This in turn will fuel a later, carnivore-based boom as the flesh-eaters chow down on the veggies.

With all this surplus food, intelligent mammals might stand a chance at beginning to develop societies. It was the existence of surplus food in the first cities that allowed humans to make the leap from ‘weirdly-clever hunter-gatherer apes’ to, well, us. Given enough space, bears could make that leap too.

8. The Dogs

If you’ve ever been to a developing nation, you know that dogs are already in charge of large swathes of the planet. In big cities like Mumbai, huge packs of feral dogs make certain areas no-go places at night. Between 1994-2015, more than 1.3 million people were attacked by dogs in this one city alone, with 434 people being savaged to death. And that’s in a city that’s still nominally run by humans.

After humans all succumb to some hideous virus, those packs would no longer have any checks on them. In the ruins of places like New York, London, and Delhi, gigantic gangs of dogs would emerge, digging through the rubble, fighting with rats for the few scraps of flesh left. It would be an unprecedented explosion in global canine populations… and it might just lead to some interesting changes.

Dogs are already capable of impressive feats of intelligence. They have complex social lives, and can show emotions roughly analogous to human feelings like empathy. In other words, those are fertile brains for evolving some level of intelligence. At the very least, they’d probably control our decaying cities through sheer numbers alone.

7. The Ants

OK, time to leave the mammals behind, and go diving into the scary world of the insects. Ants may not seem the most-likely type of creature to supplant us as masters of the Earth. But don’t be fooled by their tiny size. There’s a good argument that ants rule the world already.

Consider this: There are trillions of ants worldwide, far more than there are humans. Their total weight, if you could get them to sit on the scales long enough, would exceed ours. And they’re already ahead of most animals in the intelligence stakes. While individual ants are pretty dumb, combined they have an advantage humans don’t: the hive mind.

Ant hive minds are complex things. Ant colonies have already learned to farm various types of fungus, and have been known to rear aphids as livestock. They’ve also mastered complex forms of warfare, such as using their weakest members as frontline defense and keeping their super-soldiers at the rear. And they’ve got the means to keep expanding. Currently, there’s a super-colony of ants that covers nearly the entirety of California, and constantly wages war against a similarly-sized super-colony in Mexico. We can’t be the only ones to see the human parallels there.

6. The Pigs

Planet of the Pigs would have made a terrible movie title, but there’s a good deal more chance of it coming to pass than a world of dominant apes. While there are extremely few apes left on the planet, there is a glut of pigs worldwide. And you better believe they’re ahead of the pack in the brain department. Pigs have complex social structures and show empathy. They can socially manipulate other pigs, have long-term memories, and learn with surprising speed (also, they’re one of only a handful of animals that have sex for pleasure). By some metrics, pigs are even-more intelligent than dogs.

These are all characteristics that helped humans get to the top of the evolutionary scale. Throw in a large, global, population, and it’s possible that pigs could well evolve up to a level near where we are today. Only, you can bet that no future ‘pig-internet’ will be as hopelessly obsessed with bacon as the current version.

5. The Octopi

As we told you not so long ago, octopuses are terrifying. They’re super-strong, super-smart, can learn by watching, have mastered psychological tricks, and have brain structures so spread out through their bodies that even a headshot wouldn’t kill them. But the reasons they could take over from us go even deeper than that. They’re legitimately horrifying.

See, octopuses have big brains, relative to their body size, something important in humans. They have big eyes connected to these brains, allowing them to see almost as well as we do. We humans like to boast about our opposable thumbs. As evolutionary biology professor Dr. Russell Burke pointed out to PS Mag, octopuses essentially have 8 of them. Their tentacles are capable of manipulating tools and doing things we humans couldn’t dream of doing.

They can also learn by watching one another’s behavior, raising the prospect of complex octopus societies forming from the ashes of the human race. In fact, octopi are such good candidates for future overlords that Dr. Burke questions why they haven’t got there yet. We told you they were terrifying.

4. The Racoons

If you think about it, raccoons aren’t so dissimilar to humans. No, wait, come back. We’re gonna qualify that statement, we promise.

Most of the animals on this list stand a high chance of taking over because they’ve got complex social structures, happen to be mammals, and have an unusual degree of intelligence. As anyone who’s ever had to deal with the little D-bags cleverly opening their ‘locked’ trashcan will tell you, racoons tick all those boxes. They also already face many of the same pressures as humans do, especially in the urban environment. As those pressures increase – say, in a slow-motion apocalypse – racoon selection would get shoved towards evolutionary mutations. Mutations that could wind up hitting intelligence.

The likelihood of raccoons becoming intelligent in the same way as humans, complete with skyscrapers and automobiles and so-on, is extremely unlikely. But the idea of them slowly evolving into larger forms, before reaching consciousness, really isn’t. Like the rats above, they’d need a good few million years or so. But in a world without humans, those years are gonna seem to fly by.

3. The Cockroaches

Picture the scene. The sky burns orange. The land below is blackened and devastated. As the final mushroom cloud from the last thermonuclear blast fades away, what creature is left scuttling among the ruins of man’s ruined empire? It’s the cockroach, and he and his gruesome brethren are about to inherit the Earth.

Cockroaches are impressive in so many ways we can’t even begin to count them. They genuinely can survive nuclear exchanges, with around 10 percent of all cockroaches seemingly immune to the effects of lethal doses of radiation. They evolve at super-speed: when exterminators started lacing sugar cubes with slow-acting toxins in the mid-80s, it only took the roaches until 1993 to evolve an immunity. That would be like us getting over our aversion to arsenic or cyanide in just a couple of generations.

Oh, and they reproduce at terrifying speed. So not only would they be the most-likely candidates to survive a particularly explosive apocalypse, they’d also get their population numbers back up in no time at all. Would they ever get to some form of human-equivalent intelligence? Probably not, but give them a few million years without any competition and we’re taking no chances.

2. The Apes

Most ape species have very low numbers. That’s why there’s little chance of them replacing us as top dog in the aftermath of an apocalypse. But, and we want to be very clear about this, that’s just about the only reason. If the apocalypse were to come after some great ape-conservation program sent their numbers skyrocketing, you’d barely have to wait until the last human corpse was cold before the apes took over.

If you’ve seen any of the recent Planet of the Apes movies, you know what we’re getting at. The great apes – chimps, gorillas, orangutans and bonobos – are smart. Real smart. They can be taught to communicate via sign language. They have social hierarchies complex enough to rival our own. They can use tools. They demonstrate empathy. They learn by watching. They’ve occasionally been observed hunting with weapons. They can make plans. They’re basically us, but hairier and smellier and less-likely to spend all day messing around on Twitter.

Everything you would need for apes to reach human-level intelligence is essentially in place, then, except for one thing: an absence of humans. Now, if we all went out in a nuclear war, the apes would die with us. But if a virus was engineered to hit humanity – and only humanity – with a 100% death rate? Then it’d be time for our primate brothers to step out from the wings and get on with tearing down the Statue of Liberty.

1. The Wolbachia

Wolbachia are a specific type of bacteria, also known as the Herod Bug. And they’re not just the best candidates for ruling some future version of Earth. They’re they best candidates for ruling the Earth we live on right now.

Wolbachia are almost totally in control of the fate of thousands of species. They live within the cells of two-thirds of all insects and arthropods (spiders and mites and so-on). They infect other organisms through the eggs of a host female. Oh, and they can do stuff to you that’ll make you want to scream.

These parasitic bugs can force their host to spontaneously change sex from male to female, increasing their chances of being passed on. In more-complex organisms, they can kill off unborn males when they’re still embryos, or modify a male-host’s sperm so it can only mate with Wolbachia-infected females. To top it all off, they can modify their hosts genes, triggering evolutionary mutations. In other words, they’ve been controlling the evolutionary destiny of millions of creatures for centuries.

Of course, Wolbachia are in no danger of becoming super-intelligent. But in a post-human, post-large mammal, post-nuclear war world, when nearly every remaining species lives and reproduces at the whims of the Wolbachia, they might not need to reach high intelligence to call themselves the most-dominant lifeform on Earth.

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Where are cats? Few species that we have domesticated have done so well on their own. They are smart, adaptable, fecund, capable of living on a highly varied diet. They have colonized every place that humans have.

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